Update on my experience of using a USB security key (Yubikey) for BoA login:
I figured-out that Bitwarden (password manager) that I have as an extension on Chrome was interfering with the registration of my Yubikey. After disabling auto-fill for BoA in Bitwarden, the registration of my Yubikey went without a hitch.
So now, to login to the BoA website, I just enter my User ID and password, plug my Yubikey into a USB port, enter my PIN to my Yubikey, then touch the Yubikey, and I'm logged in to my account.
So I no longer need a USA phone number to log in. Sweet!